(a) Field of the Invention
The present invention relates to a remover composition for removing resists during a manufacturing process of semiconductor devices such as integrated circuits (IC), large scale integrated circuits (LSI) and very large scale integrated circuits (VLSI). More particularly, the present invention relates to a resist remover composition which can easily and quickly remove resist film that is cured by dry etching, ashing and ion implantation processes that have been recently emphasized due to the miniaturization and integration of circuit patterns during photolithography, and photoresist film modified by metallic side-products etched from lower metal film materials during said processes, at a low temperature, and which can minimize the corrosion of lower metal wiring during the resist removal process.
(b) Description of the Related Art
Generally, manufacturing processes of semiconductor devices comprise lithography processes that comprise forming a resist pattern on a conductive layer formed on a semiconductor substrate, and then forming a conductive layer pattern using the pattern as a mask. The resist pattern used as a mask must be removed from the conductive layer with resist remover during the stripping process after the conductive layer pattern forming process. However, since in recent very large scale integrated circuit semiconductor manufacturing, a dry etching process for forming conductive layer patterns has been conducted, it becomes difficult to remove resists in a subsequent stripping process.
In a dry etching process which replaces a wet etching process using liquid-phase acids, the etching process is conducted using a gas-phase solid-phase reaction between plasma etching gases and layers such as the conductive layer. Dry etching forms the main-stream of recent etching processes, because it is easy to control and can obtain sharp patterns. However, since during a dry etching process, ions and radicals of plasma etching gases cause complex chemical reactions with the resist film on its surface and rapidly cure it, it becomes difficult to remove the resist. Examples of dry etching include reactive ion etching (RIE), which renders it difficult to remove resist in a reproducible manner using conventional resist removers.
Another process that makes the removal of resists difficult is an ion implantation process. This process is conducted to diffuse atoms such as phosphorous, arsenic, boron, etc., in order to allow conductivity in a specific area of a silicon wafer in manufacturing processes of semiconductor devices. During this process, ions are injected only into a silicon wafer area that is not covered by the resist pattern, and simultaneously the surface of the resist pattern used as a mask in the ion implantation process is modified by a chemical reaction between the surface and accelerated ion beams. Accordingly, after the ion implantation process, it becomes difficult to remove the resist film using various solvents in a stripping process.
A resist film that has undergone the above-mentioned dry etching process or ion implantation process cannot be sufficiently removed using conventional phenol resist remover, and even if removed, inferiority rates of semiconductor devices increase because high temperature of 100° C. or more and long immersion time are required, and thus the stripping process cannot be stably conducted. For this reason, phenol resist remover is presently seldom used at a manufacturing site.
Meanwhile, a recently suggested resist remover composition comprising alkanol amine and diethyleneglycol monoalkyl ether has been widely used because it has little odor and toxicity and exhibits effective removing performance for most resist films. However, it has also been found that said remover composition cannot sufficiently remove resist film exposed to plasma etching gases or ion beams in a dry etching process or an ion implantation process. Thus, there has been a need for the development of a novel resist remover that can remove resist film modified by the dry etching and ion implantation processes.
As stated above, it is difficult to remove resist film that has undergone the ion implantation process using resist remover. Particularly, it is more difficult to remove resist film that has undergone the ion implantation process with a high radiation dose for forming source/drain area in very large scale integrated circuit manufacturing process. During the ion implantation process, the surface of the resist film is cured mainly due to reaction heat from the high energy ion beams and the high radiation dose. In addition, popping of the resist occurs which generates resist residues. Commonly, a semiconductor wafer that is ashing-treated is heated to a high temperature of 200° C. or more. At this time, solvent remaining inside the resist should be evaporated and exhausted, which is not possible because a cured layer exists on the surface of the resist after the ion implantation process with a high radiation dose.
Accordingly, as ashing proceeds, internal pressure of the resist film increases and the surface of the resist film is ruptured by solvent remaining inside, which is referred to as popping. The surface cured layer dispersed by such popping becomes residues and they are difficult to remove. In addition, since the cured layer on the surface of the resist forms by heat, impurity ions, or dopants, are substituted in the structure of resist molecules to cause a cross-linking reaction, and the reacted area is oxidized by O2 plasma. Thus the oxidized resist changes into residues and particles to become contaminants, which lowers the production yield of very large scale integrated circuit manufacture.
Many dry and wet etching processes for effectively removing the resist cured layer have been suggested, one of which is a two step ashing method comprising conducting common ashing and following with a second ashing process as described in Fujimura, Japanese Spring Application Physical Society Announcement, 1P-13, p574, 1989. However, these dry etching processes are complicated, they require a lot of equipment and they lower production yield.
In addition, a resist remover composition comprising an organic amine compound and various organic solvents has been suggested as a resist remover used in a conventional wet stripping process. Specifically, a resist remover composition containing monoethanolamine (MEA) as the organic amine compound is widely used.
As examples, a two-component system resist stripper composition comprising a) organic amine compounds such as monoethanolamine (MEA), 2-(2-aminoethoxy)ethanol (AEE), etc., and b) polar solvents such as N,N-dimethylacetamide (DMAc), N,N-dimethylformamide (DMF), N-methylpyrrolidone (NMP), dimethylsulfoxide (DMSO), carbitol acetate, methoxyacetoxypropane, etc. (U.S. Pat. No. 4,617,251); a two-component system resist stripper composition comprising a) organic amine compounds such as monoethanolamine (MEA), monopropanolamine, methylamylethanol, etc., and b) amide solvents such as N-methylacetamide (Mac), N,N-dimethylacetamide (DMAc), N,N-dimethylformamide (DMF), N,N-dimethylpropionamide, N,N-diethylbutylamide, N-methyl-N-ethylpropionamide, etc. (U.S. Pat. No. 4,770,713); a two-component system resist stripper composition comprising a) organic amine compounds such as monoethanolamine (MEA), and b) non-protonic polar solvents such as 1,3-dimethyl-2-imidazolidinone (DMI), 1,3-dimethyl-tetrahydropyrimidinon, etc. (German Laid-Open Patent Application No. 3,828,513); a resist stripper composition comprising a) ethylene oxide-introduced alkylene polyamines of alkanol amines such as monoethanolamine (MEA), diethanol amine (DEA), triethanolamine (TEA), etc., and ethylenediamine, b) sulfone compounds such as sulforane, etc., and c) glycol monoalkyl ethers such as diethylene glycol monoethyl ether, diethylene glycolmonobutyl ether, etc., in a specific ratio (Japanese Laid-open Patent Publication No. Sho 62-49355); a resist stripper composition comprising a) water soluble amines such as monoethanolamine (MEA), diethanolamine (DEA), etc., and b) 1,3-dimethyl-2-imidazolidinone (Japanese Laid-open Patent Publication No. Sho 63-208043); a positive resist stripper composition comprising a) amines such as monoethanolamine (MEA), ethylenediamine, piperidine, benzyl amine, etc., b) polar solvents such as DMAC, NMP, DMSO, etc., and c) a surfactant (Japanese Laid-open Patent Publication No. Sho 63-231343); a positive resist stripper composition comprising a) nitrogen-containing organic hydroxy compounds such as monoethanolamine (MEA), b) one or more solvents selected from diethyleneglycol monoethyl ether, diethyleneglycol dialkyl ether, -butyrolactone and 1,3-dimethyl-2-imidazolinone, and c) DMSO in a specific ratio (Japanese Laid-open Patent Publication No. Sho 64-42653); a positive resist stripper composition comprising a) organic amine compounds such as monoethanolamine (MEA), etc., b) a non-protonic polar solvent such as diethylene glycol monoalkyl ether, DMAc, NMP, DMSO, etc., and c) a phosphate ester surfactant (Japanese Laid-open Patent Publication No. Hei 4-124668); a resist stripper composition comprising a) 1,3-dimethyl-2-imidazolidinone (DMI), b) dimethylsulfoxide (DMSO), and c) organic amine compounds such as monoethanolamine (MEA), etc. (Japanese Laid-open Patent Publication No. Hei 4-350660); and a resist stripper composition comprising a) monoethanolamine (MEA), b) DMSO, c) catechol (Japanese Laid-open Patent Publication NO. Hei 5-281753) have been suggested and these resist stripper compositions show relatively good properties in terms of their stabilities, processabilities and resist removing performances.
However, one of the recent tendencies of semiconductor device manufacturing processes is treating various substrates including silicon wafers at a high temperature of 110 to 140° C., and thus resists are often baked at high temperatures. However, said resist strippers do not have sufficient capabilities for removing resists that are baked at high temperatures. As compositions for removing the hard baked resists, resist remover compositions containing water and/or hydroxylamine have been suggested. As examples, a resist stripper composition comprising a) hydroxylamines, b) alkanol amines, and c) water (Japanese Laid-open Patent Publication No. Hei 4-289866; a resist stripper composition comprising a) hydroxylamines, b) alkanol amines, c) water and d) anti-corrosives (Japanese Laid-open Patent Publication No. Hei 6-266119); a resist stripper composition comprising a) polar solvents such as GBL, DMF, DMAc, NMP, etc., b) aminoalcohols such as 2-methylaminoethanol, and c) water (Japanese Laid-open Patent Publication No. Hei 7-69618); a stripper composition comprising a) aminoalcohols such as monoethanolamine (MEA), b) water, and c) butyldiglycol (Japanese Laid-open Patent Publication No. Hei 8-123043); a resist stripper composition comprising a) alkanolamines, alkoxyamines, b) glycol monoalkyl ether, c) sugar alcohols, d) quaternary ammonium hydroxide, and e) water (Japanese Laid-open Patent Publication No. Hei 8-262746); a stripper composition comprising a) one or more alkanolamines of monoethanolamine (MEA) or AEE, b) hydroxylamine, c) diethyleneglycol monoalkyl ether, d) sugars (sorbitol), and e) water (Japanese Laid-open Patent Publication No. Hei 9-152721); a resist stripper composition comprising a) hydroxylamines, b) water, c) amines having an acid dissociation constant (pKa) of 7.5 to 13, d) water soluble organic solvent, and e) an anticorrosive (Japanese Laid-open Patent Publication No. Hei 9-96911) have been suggested.
However, said resist stripper compositions are not satisfactory in terms of either their removing performances for resist films cured by dry etching, ashing and ion implantation processes and those modified by metallic side-products etched from lower metal film materials during said processes, or anti-corrosive performances of lower metal wiring during the resist removal process.